A fastener comprising a first member and a second member is disclosed in GB2400154 A. Specifically, GB2400154 A discloses a fastening which may be useful in securing in position, within a vehicle, an air-bag of the “inflatable curtain” type. The fastening comprises a bolt. The bolt has a head and a threaded shank extending from the head. The threaded shank is dimensioned to co-operate with a predetermined threaded bore and the free end of the shank remote from the head is provided with an end cap. The end cap has a yieldable formation to engage frictionally with the threaded bore. The shank of the bolt is provided with an axially extending projection having an enlarged head, and the cap has an internal bore dimensioned to receive the projection and head. The end cap is provided with a plurality of radially outwardly extending segmented flanges. A ridge extends axially passing between adjacent flange sections. When fastenings disclosed in GB2400154 A are used to secure an inflatable curtain in position, each fastening may be passed through an aperture formed in a lug provided on the inflatable curtain so that the end cap becomes frictionally engaged within the threaded bore which is provided to received the appropriate bolt. When all of the fastenings have been inserted in position in this way, the frictional grip effected by the fastenings to the threaded bores provided in the motor vehicle will be sufficient to hold the inflatable curtain in position. By applying further axial pressure, the threaded shank of the bolt of a fastening may then be brought into engagement with the threaded aperture and the bolt may be fastening in the conventional manner.